DevTools: enable by default disableAgentsWhenProfile experiment

profilingLock was replaced with WebInspector.targetManager.suspendAllTargets/resumeAllTargets calls and TargetManager.Events.SuspendStateChanged event. 

BUG=

Review URL: https://codereview.chromium.org/614323003

git-svn-id: svn://svn.chromium.org/blink/trunk@183942 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Detach first letter pseudo element during RenderTextFragment destruction.

If the RenderTextFragment is being destroyed, make sure the pseudo element
is unlinked (Oilpan or not) during destroy() instead.

R=haraken
BUG=391288

Review URL: https://codereview.chromium.org/660413002

git-svn-id: svn://svn.chromium.org/blink/trunk@183943 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: DOM wrappers don't need to keep persistent handles

DOM wrappers don't need to create persistent handles to keep corresponding DOM objects alive. Given that V8 already knows a list of DOM wrappers, we can just iterate the DOM wrappers and trace corresponding DOM objects.

The key change of this CL is in V8GCController.cpp. V8GCController::traceDOMWrappers is called in ThreadState::visitPersistents. V8GCController::traceDOMWrappers iterates all DOM wrappers using v8::PersistentHandleVisitor and traces corresponding DOM objects.


This CL significantly improves performance of various benchmarks in oilpan.

query-selector-*.html: ~32% better
create-element.html: 15% better
indexed-getter.html: 26% better
usr-parser.html: 13% better
...

Also this CL removes a lot of complexity from the code base, e.g., WrapperPersistentNode, setNativeInfoWithPersistentHandle, setNativeInfoForHiddenWrapper etc.


BUG=420515

Review URL: https://codereview.chromium.org/651713002

git-svn-id: svn://svn.chromium.org/blink/trunk@183944 bbb929c8-8fbe-4397-9dbb-9b2b20218538